Fig. 1. Schematic of picosecond laser processing system

Fig. 2. (a) Schematic of picosecond laser processing route; (b) schematic of grating micro-nano structure

Fig. 3. Schematic of serrated morphology at bottom of grating micro-nano structure

Fig. 4. Single pulse energy density and laser ablation rate versus average power

Fig. 5. Width and depth of grating micro-nano structure versus average power

Fig. 6. Morphologies of grating micro-nano structures under different average powers. (a) 1.4 W; (b) 7.0 W

Fig. 7. Schematic of picosecond laser spot overlap

Fig. 8. Spot overlap rate and laser ablation rate versus scanning speed

Fig. 9. SEM images of grating micro-nano structures under different scanning speeds. (a) 200 mm·s-1; (b) 700 mm·s-1

Fig. 10. Width and depth of grating micro-nano structures under different scanning speeds

Fig. 11. Pulse number and laser ablation rate versus processing times

Fig. 12. Width and depth of grating micro-nano structures versus processing times

Fig. 13. 3D morphologies of grating micro-nano structures under different processing times. (a) 40; (b) 50

Fig. 14. Micro-nano structure on stainless steel surface. (a) 3D morphology; (b) SEM image